This invention relates to a method of forming an elongate, small, flat-bottomed V-groove in a paper-covered gypsum wallboard, and to novel apparatus for use in such method.
U.S. Pat. No. 4,704,837 discloses a wall panel unit formed of a single, paper-covered gypsum wallboard having spaced grooves and, laminated thereto, a sheet of bendable, rigid sheet metal in the area of each groove, each groove having a V-shape of about 100.degree., with the bottom cover sheet undisturbed and preferably a bare strip of the bottom cover sheet, about 1/8 inch wide, being exposed. There is no mention of any recommended method or apparatus for forming the V-shaped groove.
U.S. Pat. No. 4,000,594 discloses a wall panel unit formed of a single, paper-covered gypsum wallboard having spaced grooves, the sides of which are perpendicular to each other, which grooves, in the preferred embodiment, may be milled or otherwise formed by cutting tools, with no bare strip of the bottom cover sheet exposed.